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About RCgothic

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    Spacecraft Engineer

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  1. Well I feel sheepish. I must have been overcomplicating my search terms.
  2. What are Soyuz's exact numbers? I've struggled to find them in my own searches.
  3. F9 B5 has now had 19 successes from 19 missions. The success rate based on Bayesian statistics is: P{S} = (n{S}+1)/(n+2) Where: P{S}= Probability of mission success n{S}= Number of successes n = Number of attempts P{S}= 95.2% For falcon 9 as a whole, it's 76 successes from 78, or 96.3% That has to be close to an industry leader surely.
  4. It's not the composition (identical), it's the behaviour. If you've seen the scene in "Passengers" where the gravity turns off and the effect that had on the swimming pool you'll have some idea. Water in zero g is sticky. It forms balls. It clings to things and covers surfaces. There's no buoyancy, so you can't escape by letting yourself float. Which way is out? Then when you do get to the surface it clings and distends around you, refusing to let you go. Found an external handhold to pull yourself out? It'll cling to that too and come with you. It's far too difficult to get out of. In zero g large quantities of water is an extreme drowning hazard. The moon has gravity so it would be far less hazardous to have your swimming pool there.
  5. Pretty sure that much free water in zero gravity would be an extreme hazard. At least some gravity/spin is required at a minimum. Plus it's heavy, a tonne per m3. It's not something you want to be carrying around on a spacecraft unless it serves dual purpose. That said, I've heard that if you had a swimming pool on the moon, humans would be able to leap like dolphins. If you were using hydrolox as power, then that's worth taking to the moon for that alone. You could then condense the products and make use of the water byproduct to create the solar system's best water park!
  6. I wonder if red components are a colour code for "not for flight", e.g. supports or blanking plugs that need to be removed before the rocket reaches the pad.
  7. Twice the money, eight times as many first stages. I guess the relationship of space expenditure to rockets is cubic.
  8. They claim 98% efficiency and an exhaust imparted with so much energy it burns blue. But the only available stats are from their own promotional materials and it hasn't had a full-scale test - yet. 365s is 6s better than the best available vacuum engine right now. I can *just* believe that there's 6s to be had out of a monolithic 3D printed combustion chamber, but wow even so.
  9. Sounds like it could be possible damage caused by rough seas yesterday. Seas are calm today, so that's not the reason.
  10. Interestingly, 15,400kg to LEO is over 90% of Falcon 9 FT's nominal payload to LEO (reusable) according to Wikipedia. I remember people saying payload to LEO is a nominal value for comparison that could never actually be used, and that the payload adaptors can't handle it. Wikipedia actually lists the F9 B5 PFA structural limit as less than 11te! I guess payload to LEO isn't so nominal anymore.
  11. According to Reddit, May's launch was 227kg per sat, ~13,670kg total. On this launch it's up to 260kg per sat, 15,400kg total. So the sats are indeed heavier. It may be as sh1pman says, material changes due to burn-up concerns, or they may simply be more capable. May's launch was v0.9 prototypes, whereas this is officially the Starlink-1 mission.
  12. It's been said again and again. SLS/Orion isn't the rocket/spacecraft combo we need. For LEO assembly it's too expensive, flies too infrequently, and has nowhere near enough dwell time with a hydrolox upper stage. For BEO operations it doesn't have enough throw weight to accomplish anything meaningful in a single mission. Which brings us straight back to too expensive, flies too infrequently, and has nowhere near enough dwell time, because the lack of throw weight makes rendezvous a necessary mission requirement. You don't need a big man-rated (and therefore expensive) booster for getting a crew to orbit anymore. Rendezvous is a solved problem. Ares absolutely had the right idea (minus the bonkers srb design). You want a big dumb booster that's payload agnostic, inexpensive, and can fly frequently. 200t to orbit. Then you'd have a range of things you could stick on top of it to suit the mission. It doesn't have to be fancy, or have great BEO performance. That much is handled by the payload. It just needs to get to LEO as cheaply and as often as possible.